The Green Mosque of Iznik (Turkish: Yeşil Camii) is a historic Ottoman mosque in Iznik, Turkey.

One of the earliest examples of Ottoman architecture, the mosque was built by order of the Grand Vizier, Halil Pasha Chandrali the Great, from Sultan Murad I of Iznik. It was completely built by his son, Ali Pasha. The inscription on the mosque gives the date of construction 780-794 AH (1378-1391 AD) and the name of the architect (Hajji bin Musa).

The mosque is located near Lefka Gate on the eastern side of the city. It consists of three porticoes, one musalla (prayer hall), and one dome, 10.5 meters (34 ft) in diameter. It is 17.5 meters (57 ft) high from the ground, and has four windows. The lower part of the interior walls is sheathed with gray marble panels.

The mosque has one minaret in the northwest corner of the building.

The mosque was damaged in 1922 by the Greek army during the Turkish War of Independence. It was restored between 1956 and 1969.